Conventional monolithic refractory depositing methods for repairing a molten metal container, such as a ladle, or constructing a new molten metal container are classified into spraying methods and casting methods.
Repairing methods using spraying are classified into dry spraying methods and wet spraying methods. A dry spraying method conveys refractory powder to a spraying nozzle by the agency of compressed air, mixes water or binder into the refractory powder in the spraying nozzle to produce refractory slurry, and sprays the refractory slurry by the agency of compressed air. A wet spraying method mixes refractory powder and water to produce a refractory mixture, kneads the refractory mixture to produce refractory slurry, sends the refractory slurry through a spraying pipe by a pump, adds a binder to the refractory slurry in a spraying nozzle, and sprays the mixture of the refractory slurry and the binder by the agency of compressed air onto a desired surface.
A casting method, differing from the spraying method, assembles a form at the site, pours refractory slurry prepared by kneading a mixture of water and a refractory material into the form. Although a refractory structure constructed by a casting method has a dense texture and a long life, the construction of such a refractory structure needs a form inevitably.
Recently, there is a trend to use a wet spraying method capable of forming a high-quality refractory structure having durability comparable to that of a refractory structure formed by a casting method, and satisfactory in homogeneity.
The spraying method is carried out by hand spraying work (manual spraying work requiring an operator to hold and operate a nozzle by hand) or mechanical spraying work using a nozzle driving device. When carrying out the spraying method by hand spraying work, the operator needs to move the heavy nozzle by human power, which requires heavy manual work. Furthermore, the spraying method employing hand spraying has drawbacks that the operator working at the site is exposed to injurious rebound loss and dust, and different operators places the material in different thicknesses.
Although dry nozzle driving devices of various types for driving a spray nozzle have been developed for the dry spraying method, any wet nozzle driving device for driving a spray nozzle, suitable for the wet spraying method has not been developed yet.
As mentioned above, the casting method assembles a form at the site, and pours refractory slurry into the form by a belt conveyor or a chute. Recently, a pump capable of forcibly pumping a highly viscous material has been developed. Most recent casting methods convey a material through hoses by force feed to a casting place.
However, the casting method also needs inefficient, heavy manual work to carry a heavy nozzle to the casting place.
Incidentally, the employment of either the spraying method or the casting method is suitable for some repairing work or construction work, and the employment of both the spraying method and the casting methods is suitable for other repair work or construction work. So far, any construction system capable of executing both the spraying method and the casting method has not been developed. Therefore, when construction work needs to carry out both the spraying method and the casting method, both construction apparatuses for carrying out the spraying method and the casting method must be kept at the site and the construction apparatuses must be changed and necessary one of the construction apparatuses must be installed in place. Work for changing the construction apparatuses takes much time, equipment cost increases because a plurality of construction apparatuses are necessary, and increased maintenance work is necessary for the maintenance of the plurality of construction apparatuses.